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Difference between revisions of "cpp/named req/CopyAssignable"

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< cpp‎ | named req
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{{cpp/concept/title|CopyAssignable}}
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{{cpp/named req/title|CopyAssignable}}
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{{cpp/concept/sidebar}}
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{{cpp/named req/navbar}}
  
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Specifies that an instance of the type can be copy-assigned (copied).
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Specifies that an instance of the type can be copy-assigned from an [[cpp/language/value_category|lvalue expression]].
  
 
===Requirements===
 
===Requirements===
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The type {{tt|T}} satisfies {{named req/core|CopyAssignable}} if
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* The type {{tt|T}} satisfies {{named req|MoveAssignable}}, and
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Given
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* {{tt|t}}, a modifiable [[cpp/language/value_category|lvalue expression]] of type {{tt|T}},
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* {{tt|v}}, an [[cpp/language/value_category|lvalue]] expression of type {{tt|T}} or {{tt|const T}} or an [[cpp/language/value_category|rvalue]] expression of type {{tt|const T}}.
  
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The type must implement the following functions:
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The following expressions must be valid and have their specified effects.
  
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{{member | 1={{dcl small|Type::}}operator= | 2=
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{|table class=wikitable
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|-
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!Expression||Return type||Return value||Post-conditions
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|-
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|{{c|1=t = v}}
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|{{tt|T&}}
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|{{tt|t}}
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|The value of {{tt|t}} is equivalent to the value of {{tt|v}}.
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The value of {{tt|v}} is unchanged.
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|}
  
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{{ddcl | notes={{mark|One of the variants is sufficient}} | 1=
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===See also===
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Type& Type::operator=( Type& other );
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{{dsc begin}}
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Type& Type::operator=( const Type& other );
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{{dsc inc|cpp/types/dsc is_copy_assignable}}
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Type& Type::operator=( volatile Type& other );
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{{dsc inc|cpp/concepts/dsc assignable_from}}
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Type& Type::operator=( const volatile Type& other );
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{{dsc end}}
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}}
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[[cpp/language/copy_operator|Copy assignment operator]]: assigns the contents of {{tt|other}}. The internal state of {{tt|other}} must not be modified.
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{{langlinks|de|es|fr|it|ja|pt|ru|zh}}
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The following expressions must have the specified effects:
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{{tdcl list begin}}
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{{tdcl list hitem | Expression | Effects}}
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{{tdcl list item | {{cpp|1=a = v;}} | {{tt|a}} is equivalent to {{tt|v}}, where {{tt|a}} is an instance of {{tt|Type}} and {{tt|v}} is an instance of {{tt|Type}}. {{tt|v}} must be unchanged.}}
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{{tdcl list end}}
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}}
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===See also===
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{{dcl list begin}}
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{{dcl list template | cpp/types/dcl list is_copy_assignable}}
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{{dcl list end}}
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Latest revision as of 10:36, 8 August 2023

 
C++
 
C++ named requirements
 

Specifies that an instance of the type can be copy-assigned from an lvalue expression.

[edit] Requirements

The type T satisfies CopyAssignable if

Given

The following expressions must be valid and have their specified effects.

Expression Return type Return value Post-conditions
t = v T& t The value of t is equivalent to the value of v.

The value of v is unchanged.

[edit] See also

(C++11)(C++11)(C++11)
 checks if a type has a copy assignment operator
(class template) [edit]
(C++20)
 specifies that a type is assignable from another type
(concept) [edit]
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